1. Field of the Invention
The present invention relates to an improved hole punching and reinforcement device for positioning a length of adhesive tape over a flat sheet of material to be reinforced, punching a hole in both the tape and the sheet of material, and shearing off the punched length of tape.
2. Description of the Prior Art
One defect in many prior punch and reinforcement devices is that there is no safeguard to prevent operation of the device to both advance a length of tape and punch a hole therethrough in the absence of a sheet of material in registration with the punch. Thus, if the tape feed mechanism is left in the engaged condition and the punch is then operated without inserting a sheet of material to be reinforced into registration between the punch and the die, a section of tape at the end of the length of tape will be advanced in between the punch and the die, and pressed against the die. If no sheet of material to be punched has been inserted, the section of adhesive tape will thereupon be sheared off and remain adhesively secured to the die.
Lengths of tape so applied in the absence of a sheet of material become stacked and adhesively secured to each other, one atop of the other, so as to block the subsequent insertion of a sheet of material to be punched and reinforced. The device is then rendered inoperative until the layers of sheared sections of tape are removed from the die. This can only be accomplished by partial disassembly of the device and is a time consuming and annoying task.
My prior U.S. Pat. No. 4,826,561 describes a hole punching and reinforcing device which is operable to position a length of tape over a flat sheet of material, such as paper, and to punch a hole through both the length of tape and the paper while pressing the adhesive coated side of the tape against the paper and shearing off the length of tape from the roll of tape from which it is supplied. In an alternative mode that device is operable to punch a hole in a sheet of material without reinforcing it with tape.
In my prior U.S. Pat. No. 4,826,561 a pair of electrical switches were provided to prevent the operation of the device in the absence of a sheet of material inserted therein. The switches are actuated by the edge of the sheet of the material and generate electrical signals, both of which are necessary for the electrical actuation of the punching mechanism. However, this prior system requires an electrical power supply for its operation.
Also, in the hole punching and reinforcing device of my U.S. Pat. No. 4,826,561 a number of gears are employed to advance tape from a roll, and a clutch mechanism is provided with a selectively operable inhibiting stop that disengages the clutch mechanism. The stop is manually actuated to allow a user either to punch holes in sheets of material without reinforcing the area surrounding the holes with tape, or to advance tape under the control of the punching mechanism so that a length of tape is advanced and applied to the sheet of material with each operation of the punching mechanism.
While the prior device of U.S. Pat. No. 4,826,561 is quite effective in its operation, I have discovered that certain significant improvements can be made in such a device. Specifically, I have devised a system which eliminates the requirement for an electric power supply, yet still provides a safeguard to prevent tape from being fed into the die and pressed thereon unless a sheet of paper is present between the tape and the die.
A further disadvantage of my prior device, as well as other conventional hole punching and reinforcing devices, is the relative complexity of the tape feed mechanism. In prior conventional devices, such as that of U.S. Pat. No. 4,826,561, tape is fed from a roll of tape that is cradled in a base. To obtain tractional engagement of the sticky side of the tape with disks for advancing the tape, the free end of the tape must be threaded beneath an idler or guide roller that is mounted in the base and over a traction drive. The process for threading the free end of the tape beneath the roller is sometimes time consuming and difficult, since the sticky side of the tape will tend to cling to the structural parts of the base or fold back upon and cling to itself as it is pushed beneath the roller. Thus, there can be a considerable expenditure of time and waste of tape that occurs during the installation of each replacement roll of tape.
Another problem that occurs with prior conventional devices is that the adhesive from the passing tape builds up on the structures defining the path of travel of the tape over a period of time. This build-up of adhesive eventually is sufficient to impair the smooth movement of tape along its path of travel toward the punching mechanism. Furthermore, the multiple gear system employed in the puncher and reinforcer of U.S. Pat. No. 4,826,561 contributes significantly to the cost of manufacture of such a conventional hole punching and reinforcing device. Other defects exist in prior conventional hole punching and reinforcing devices as well.